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Finding the view Hadi Tok CitizenMe @hadi_tok

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findViewById(int id)

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View.findViewById(int id) /** * Finds the first descendant view with the given ID, the view itself if * the ID matches getId(), or null if the ID is invalid */

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View.findViewById(int id) Generally used to access views generated with LayoutInflater

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LayoutInflater

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LayoutInflater /** * Instantiates a layout XML file into its corresponding View */

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@Override public void setContentView(@LayoutRes int layoutResID ) { getDelegate().setContentView( layoutResID ); }

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LayoutInflater.from(mContext).inflate( layoutResID , contentParent);

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final XmlResourceParser parser = res.getLayout( layoutResID );

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final String name = parser .getName();

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clazz = mContext.getClassLoader().loadClass( prefix != null ? (prefix + name) : name ).asSubclass(View.class);

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constructor = clazz .getConstructor(mConstructorSignature);

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final View view = constructor .newInstance(args);

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root.addView( view , params);

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findViewById(int id)

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@Override public T findViewById(@IdRes int id) { return getDelegate().findViewById( id ); }

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return (T) mWindow.findViewById( id );

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return getDecorView().findViewById( id );

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if ( id == mID) { return (T) this; }

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for (int i = 0; i < len; i++) { View v = mChildren[i]; v = v.findViewById( id ); if (v != null) { return (T) v; } } return null;

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Data Binding

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Data Binding Allows you to bind UI components in your layouts to data sources in your app using a declarative format rather than programmatically

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Data Binding Allows you to bind UI components in your layouts to data sources in your app using a declarative format rather than programmatically

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Data Binding Allows you to bind UI components in your layouts to data sources in your app using a declarative format rather than programmatically

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https://viblo.asia/p/understanding-data-bindings-generated-code-and-how-does-android-data-binding-compiler-work-Ljy5Vd1yZra

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public class MainActivity extends AppCompatActivity { @Inject MainViewModel viewModel; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ActivityMainBinding bind = DataBindingUtil.setContentView(this, R.layout.activity_main); bind.setViewModel(viewModel); } }

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public class MainViewModel extends ViewModel { public final ObservableField text = new ObservableField<>(); }

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https://viblo.asia/p/understanding-data-bindings-generated-code-and-how-does-android-data-binding-compiler-work-Ljy5Vd1yZra

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false

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public class ActivityMainBinding extends android.databinding.ViewDataBinding { … /** * Where the magic happens */ }

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Kotlin Android Extensions(Synthetics)

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Kotlin Android Extensions plugin Allows us to obtain the same experience we have with some of these libraries, without having to add any extra code.

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apply plugin: 'kotlin-android-extensions'

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androidExtensions { experimental = true }

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res/layout/activity_free.xml

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res/layout/activity_free.xml import kotlinx.android.synthetic.activity_free.*

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res/layout/activity_free.xml import kotlinx.android.synthetic.activity_free.* textView.text = “DevFest"

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import kotlinx.android.synthetic.main.activity_splash.* class PresentationActivity: BaseActivity() { override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) { super.onCreate(savedInstanceState, persistentState) setContentView(R.layout.activity_splash) logoIv.visibility = View.VISIBLE } }

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public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) { super.onCreate(savedInstanceState, persistentState); this.setContentView(-1300174); ImageView var10000 = (ImageView)this._$_findCachedViewById(id.logoIv); Intrinsics.checkExpressionValueIsNotNull(var10000, "logoIv"); var10000.setVisibility(0); }

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private HashMap _$_findViewCache; public View _$_findCachedViewById(int var1) { if (this._$_findViewCache == null) { this._$_findViewCache = new HashMap(); } View var2 = (View)this._$_findViewCache.get(var1); if (var2 == null) { var2 = this.findViewById(var1); this._$_findViewCache.put(var1, var2); } return var2; }

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View Binding

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View Binding Is a feature that allows you to more easily write code that interacts with views. Once view binding is enabled in a module, it generates a binding class for each XML layout file present in that module.

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android { ... viewBinding { enabled = true } }

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private lateinit var binding: ResultProfileBinding @Override fun onCreate(savedInstanceState: Bundle) { super.onCreate(savedInstanceState) binding = ResultProfileBinding.inflate(layoutInflater) setContentView(binding.root) }

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binding.name.text = viewModel.name binding.button.setOnClickListener { viewModel.userClicked() }

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Jetpack Compose

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Jetpack Compose Android’s modern toolkit for building native UI

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class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContent { Greeting("Android") } } } @Composable fun Greeting(name: String) { Text(text = "Hello $name!") }

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Questions?

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Hadi Tok, CitizenMe @hadi_tok Thank you!